The invention relates to the field of electrical switches, and is applicable to the design configuration of a vacuum interrupter in which, in order to carry out the functions of xe2x80x9cswitchingxe2x80x9d, xe2x80x9cdisconnectionxe2x80x9d and xe2x80x9cgroundingxe2x80x9d, the housing contains three contacts and has a grounding connection, which is in the form of a metallic area of the housing.
In a known vacuum interrupter of this type, the metallic part of the housing is formed from a cylinder in which insulators are inserted, which are in the form of annular disks at the ends. A current supply bolt of a first contact system, which is arranged concentrically with respect to the axis of the housing, passes axially through each of the two insulators, with the current supply bolt of the stationary contact of the first contact system being soldered to one of the insulators in a vacuum-tight manner. The current supply bolt of the moving contact of the first contact system is passed through a hole in the other insulator such that it can move. The rearward part of the moving contact of the first contact system at the same time forms the moving contact of a second contact system, which is arranged coaxially with respect to the first contact system and whose stationary contact is in the form of an annular disk and is connected in the edge area to the metallic part of the housing. A grounding contact is arranged at one of the ends of this housing. The first contact system also has an associated shield, which is in the form of a cylinder which is supported on the metallic cylinder via an annular insulating piece.
Furthermore, for medium-voltage switchgear assemblies, a switch disconnector is known in which at least two contact pairs are arranged in a common vacuum vessel, and in which the plasmas in the contact pairs are physically isolated from one another by special shields. For this purpose, two coaxial shielding cylinders, whose cylinder walls overlap in the axial direction, may be used for each contact pair. The shielding cylinders are in this case electrically conductively connected to a respective one of the contacts of the associated contact pair. Each contact pair may furthermore have an associated ground contact, to which the moving switching contact can be connected. In this case, the moving switching contact can be fixed in three switch positions.
According to an aspect of the invention, a design configuration which satisfies the practical requirements such as simple construction and cost-effective production is provided.
According to the invention, a first contact system has radial or axial magnetic field contact pieces and for the second contact system has contact pieces which are each arranged by a contact support and are in the form of annular disks. The contact support of one of the contact pieces, which is in the form of an annular disk, is arranged on the bottom face of the moving radial or axial magnetic field contact. The contact support of the other contact piece, which is in the form of an annular disk, forms the ground connection. Furthermore, the two insulators are tubular and are connected to one another at the ends with the interposition of the grounding connection, with one of the insulators surrounding the first contact system and essentially also the moving contact of the second contact system. Finally, the shield is in the form of a labyrinth shielding system in order to physically isolate plasma in the first contact system from plasma in the second contact system. The shielding system comprises a tube which surrounds the first contact system, and, together with the contact support, which is arranged on the moving contact, of the contact which is in the form of an annular disk, forms a cap.
With the vacuum interrupter configured in this way, normal components and normal manufacturing measures can generally be used for the construction and production of the vacuum interrupter, so that the vacuum interrupter can be produced economically. The use of magnetic field contact pieces and the configuration of the shield as provided in this case ensure the electrical performance of the interrupter.
The use of tubular insulators, in particular ceramic insulators, is normal per se for vacuum interrupters, as is the configuration of the contact pieces as radial or axial magnetic field contacts.
Since the second contact system need be designed only for the required make-proofing, a simple plate or annular disk geometry is sufficient for the corresponding contact pieces; a material based on copper/chromium is preferably used as the make-proof contact material. If necessary, for further design simplification, the contact support of the moving contact piece may be formed integrally with the tube which surrounds the first contact system. In this case, it is also possible for the contact support, with appropriate shaping, to at the same time form the moving contact piece, which is in the form of an annular disk. shield, it is recommended that the distance between the tube and the insulator which surrounds the contact system be chosen to be shorter than the distance between the tube and the first contact system.